Exhibit 99.1 EXPLANATION OF RESPONSES (1) Pursuant to a Note Purchase Agreement, dated as of December 4, 2003, by and among Micro Therapeutics, Inc. (the "Company"), Warburg, Pincus Equity Partners, L.P., a Delaware limited partnership (together with...Note Purchase Agreement • February 3rd, 2004 • Warburg Pincus LLC • Surgical & medical instruments & apparatus
